Technological and Safety Attributes of Lactic Acid Bacteria and Yeasts Isolated from Spontaneously Fermented Greek Wheat Sourdoughs.

Maria K. Syrokou,Loulouda Bosnea,Sofia Tziompra,Sofia-Despoina Mpisti,Eleni-Efthymia Psychogiou,Panagiotis N. Skandamis,Marios Mataragas,Eleftherios H. Drosinos,Spiros Paramithiotis

doi:10.3390/microorganisms9040671

Maria K. Syrokou, Loulouda Bosnea + Show 7 more

Open Access

https://doi.org/10.3390/microorganisms9040671

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Abstract

The aim of the present study was to assess the technological and safety potential of 207 lactic acid bacteria (LAB) and 195 yeast strains isolated from spontaneously fermented Greek wheat sourdoughs. More accurately, the amylolytic, proteolytic, lipolytic, phytase and amino acid decarboxylase activities, along with the production of exopolysaccharides and antimicrobial compounds by the LAB and yeast isolates, were assessed. A well diffusion assay revealed seven proteolytic LAB and eight yeast strains; hydrolysis of tributyrin was evident only in 11 LAB strains. A further Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) indicated partial hydrolysis of gluten. Lipolysis kinetics over 21 days was applied, exhibiting that lipolytic activity ranged from 6.25 to 65.50 AU/mL. Thirteen LAB inhibited Penicillium olsonii and Aspergillus niger growth and 12 yeast strains inhibited Pe. chrysogenum growth. Twenty-one Lactiplantibacillus plantarum strains exhibited inhibitory activity against Listeria monocytogenes, as well as several sourdough-associated isolates. The structural gene encoding plantaricin 423 was detected in 19 Lcb. plantarum strains, while the structural genes encoding plantaricins NC8, PlnE/F, PlnJ/K, and S were detected in two Lcb. plantarum strains. None of the microbial strains tested exhibited exopolysaccharide (EPS) production, amino acid decarboxylase, amylolytic or phytase activity. The technological and safety potential of the Lcb. plantarum and Wickerhamomyces anomalus strains was highlighted, since some of them exhibited proteolytic, lipolytic, antibacterial and antimould activities.

Highlights

Lactic acid bacteria and yeast isolates were grown twice in de Mann, Rogosa, and Sharpe (MRS) broth, and in Brain Heart Infusion (BHI) broth, and their purity was examined through streaking in MRS agar and BHI agar, respectively
The agar well diffusion assay revealed that, of the 207 lactic acid bacteria (LAB) and 195 yeast strains initially screened for proteolytic activity, seven and eight strains, respectively, were able to hydrolyze gluten
In the case of yeasts, four isolates were assigned to S. cerevisiae (LQC 10343, 10378, 10398, 10402), three to W. anomalus (LQC 10346, 10353, 10360), and one to Pi. fermentans

Summary

Introduction

Within the past few years, the ever-increasing consumer demand for “clean label”. Products has shifted the technological interest of baking industries towards the development of more ecologically friendly methods of preserving foods, such as sourdough fermentation [1]. The incorporation of sourdough into bread making imparts positive effects on all aspects of bread quality, namely technological, sensorial, safety and nutritional attributes. The production of microbial metabolites, which further affect the quality of the end product, is highly dependent on the contribution of lactic acid bacteria (LAB) and yeast strains, which form the sourdough microecosystem [2]. Suitable starter cultures with defined metabolic properties should be carefully selected to assure the reproducibility 4.0/).

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